Repair Service Manual

REPAIR MANUAL
1
KUBOTA Z402 and Z602 engines
TIGHTENING TORQUES Z402
The screws, bolts and nuts must be tightened at the torque specified using a torque wrench.
Several screws, bolts and nuts, such as those on the cylinder head, must be tightened in a specific sequence and
torque.
1. Tightening torques for screws, bolts and nuts for particular use
 For screws, bolts and nuts marked « * » in the table, smear the threading and seats with motor oil before
tightening.
 The letter « M » of dimension x pitch means that the dimension of the screw, bolt or nut relies on the metric
system.
 The dimension is the nominal outer diameter of the threadings in mm.
 The pitch is the nominal distance in mm between two threads.
Element
Dimension x pitch
N-m
Kgf-m
* Cylinder head cover nuts
M6 x 1.0
3.9 to 5.9
0.4 to 0.6
* Cylinder head screws
M8 x 1.25
37.2 to 42.1
3.8 to 4.3
* Main bearing fastening screw 1
M6 x 1.0
12.7 to 15.7
1.3 to 1.6
* Main bearing fastening screw 1 (flywheel side)
M8 x 1.25
23.5 to 27.4
2.4 to 2.8
* Main bearing fastening screw 2
M7 x 1.0
26.5 to 30.4
2.7 to 3.1
* Flywheel screws
M10 x 1.25
53.9 to 58.8
5.5 to 6
* Piston rod screws
M7 x 0.75
26.5 to 30.4
2.7 to 3.1
* Rocker arm support nuts
M6 x 1.0
9.8 to 11.3
1.00 to 1.15
* Gear shaft screw
M6 x 1.0
9.8 to 11.3
1.00 to 1.15
* Crankshaft end bolt
M12 x 1.5
117.6 to 127.4
12.0 to 13.0
* Bearing box cover screws
M6 x 1.0
9.8 to 11.3
1.00 to 1.15
Glow plugs
M8 x 1.0
7.8 to 14.7
0.8 to 1.5
Injector holder assembly
M20 x 1.5
49.0 to 68.6
5.0 to 7.0
Oil pressure switch tapered screw
PT 1/8
14.7 to 19.6
1.5 to 2.0
Injection duct fastening nuts
M12 x 1.5
24.5 to 34.3
2.5 to 3.5
Overflow pipe assembly fastening nuts
M12 x 1.5
19.6 to 24.5
2.0 to 2.5
Starter nut B terminal fitting nut
M8
8.8 to 11.8
0.9 to 1.2
2. Tightening torques for screws, bolts and nuts for general use
When tightening torque values are not specified, tighten the screws, bolts, and nuts at the values specified in the
following table.
Grade
Standard screws and
bolts 4
Special screws and
bolts 7
Unit
N-m
Kgf-m
N-m
Kgf-m
Nominal diameter
M6
7.9 to 9.3
0.80 to 0.95
9.8 to 11.3
1.00 to 1.15
M8
17.7 to 20.6
1.8 to 2.1
23.5 to 27.5
2.4 to 2.8
M10
39.2 to 45.1
4.0 to 4.6
48.1 to 55.9
4.9 to 5.7
M12
62.8 to 72.6
6.4 to 7.4
77.5 to 90.2
7.9 to 9.2
The material grade is indicated by numbers engraved on the heads of screws and bolts. Always check the numbers
indicated below before tightening.
Number
engraved
Material grade of the screw or bolt
None or 4
SS41, S20C screw and bolt
7
S43C, S48C special screw and bolt
(refined)